At the top of the mountains lies a monument called “Monte de la Pedraja” dating back to 1936. It is a tribute to the 300 victims who were assassinated nearby for their political beliefs during the first few months of the Spanish Civil War. The killings were orchestrated by the brutal dictator Francisco Franco.

The monastery and its accompanying church were built on the site of a pilgrim´s hospice and monastery founded by San Juan de Ortega, the disciple and companion of Santo Domingo de la Calzada, in the early 12th century. The site chosen by San Juan was the wild and barren wastes of the Montes de Oca, much-feared by medieval pilgrims as a haven for bandits and consequently regarded as one of the most dangerous stretches of the entire medieval route. The small hospice and monastery with their accompanying church provided a safe and welcome halt for pilgrims making the long and dangerous crossing through the area.

Despite its isolation, the monastery attracted the attention of nobles, kings and popes alike. King Alfonso VII of Castile chose San Juan as his personal confessor and visited the monastery on several occasions; he also made several important grants of land and money to the monastery in order to assure its maintenance. In 1138 Pope Innocent II offered his personal protection to San Juan and the monastery, and on two occasions in the 15th century Queen Isabella the Catholic visited the saint´s tomb, praying for the birth of a child. The results on both occasions were favorable: first Prince John of Austria and later Princess Joanna of Castile were born following the Queen´s pilgrimages to the tomb of San Juan.

Though the monastery has long since been abandoned by the monks who once lived here, there is a modest pilgrim´s refuge here even today. The monastery church contains the crypt where San Juan de Ortega is buried, and the Gothic baldachin which crowns it is remarkable for the delicacy of its tracery. A series of capitals on the left side of the apse depict scenes from the life of the Virgin and Christ-the Annunciation, the Visitation and the Nativity. The Annunciation capital is of particular interest because it appears to serve as a calendar marking the equinoxes-on 21 March and 22 September each year a ray of sunlight enters the church at twilight, illuminating the scene of the Archangel Gabriel´s apparition to the Virgin Mary, announcing that she was to be the Mother of Christ.